ACADEMIC & RESEARCH INTEREST

My laboratory is interested in the mechanisms that regulate contraction of smooth muscles. We use biophysical, structural, and kinetic techniques to study the structure and function of myosin and actin, the major contractile proteins. These studies are addressing the structural mechanisms that control the activity of myosin. Smooth muscle myosin is regulated by phosphorylation, resulting in large conformational changes. The inactive unphosphorylated state is self-inhibited by interaction of the myosin tail domain with the catalytic and regulatory domains. We are studying the structure of this inhibited state by photocross-linking, fluorescence quenching and polarization, electron paramagnetic resonance, phosphorescence anisotropy, mass spectrometry and crystallography. Self-inhibited myosin is in equilibrium with myosin filaments, which is the force-generating conformation.

We are interested in understanding the regulation of this equilibrium in the cell. Major approaches are measurements of contractile force in intact tissues, immunofluorescence microscopy of transiently-transfected cells, dynamic imaging of GFP- and other fluorescent constructs in live cells, mutagenesis, and fluorescence photo-bleaching recovery.

COURSES & TEACHING RESPONSIBILITIES

Medical Biochemistry 602

ACCOMPLISHMENTS

NIH grant in 17th year of continuous funding

Topographical Studies of Smooth and Nonmuscle Myosins

Co-PI for COBRE, Smooth Muscle Plasticity, University of Nevada School of Medicine

Member - American Heart Association Study Section, Molecular Biology of the Muscle (1999-2001)

Editorial Board Member, Journal of Biological Chemistry (2001-2006)

Member – National Institute of Arthritis and Musculoskeletal Disease, 2001 Site Visit Team, Program Project Grant Review for University of Vermont, Department of Molecular Physiology and Biophysics, College of Medicine, Myosin Dynamics during the Contractile Cycle

The smooth muscle isoform of myosin light chain kinase (MLCK) is a Ca2+-calmodulin-activated kinase that is found in many tissues. It is particularly important for regulating smooth muscle contraction by phosphorylation of myosin. This review summarizes selected aspects of recent biochemical work on MLCK that pertains to its function in smooth muscle. In general, the focus of the review is on new findings, unresolved issues, and areas with the potential for high physiological significance that need further study. The review includes a concise summary of the structure, substrates, and enzyme activity, followed by a discussion of the factors that may limit the effective activity of MLCK in the muscle. The interactions of each of the many domains of MLCK with the proteins of the contractile apparatus, and the multi-domain interactions of MLCK that may control its behaviors in the cell are summarized. Finally, new in vitro approaches to studying the mechanism of phosphorylation of myosin are introduced.